Polyaluminoxane compositions in solution are condensation products generally prepared by partial hydrolysis of organic aluminum compounds. They are known to be useful as promoter (co-catalytic) components that efficiently activate transition metal compounds serving as primary catalysts in the manufacturing of olefin polymers. Polymethylaluminoxane compositions in which trimethylaluminum is employed as a starting material organic aluminum compound are widely known to exhibit particularly good performance as promoters. These compositions can usually be handled in solution form when dissolved in an aromatic hydrocarbon solvent such as toluene (see Patent References 1 to 6 and the like).
Polymethylaluminoxane compositions exhibit good promoter's performance. However, they are normally handled in a state in which a polymethylaluminoxane composition is dissolved in a solvent with a primary catalyst such as a metallocene compound, and the morphology of the polymer produced cannot be controlled. Thus, not only does handling of the polymer become difficult, but there is a problem in that fouling due to adhesion of the polymer to the polymerization reaction vessel or the like is highly prone to occur.
To solve these problems, a method of applying a supported solid polymethylaluminoxane composition, in which a polymethylaluminoxane composition is supported on a solid inorganic support such as silica, alumina, or magnesium chloride, to suspension polymerization or vapor phase polymerization has been proposed. Among solid inorganic supports, silica with a controlled quantity of surface hydroxyl groups is the most widely employed, and there are quite a few examples of extension to the industrial level (see Patent References 7 to 11, 17, and the like).
The silica support tends to remain in the polymer and is known to compromise the performance of the polymer. Further, solid polymethylaluminoxane compositions in which such a support is employed are known to exhibit much lower activity than the polymerization activity in homogeneous polymerization. Accordingly, to solve these problems, the development of a solid polymethylaluminoxane composition having high activity rivaling that of homogeneous polymerization while retaining the advantages of a promoter in the form of a solid polymethylaluminoxane composition has been eagerly awaited.
Attempts have been made to obtain a solid polymethylaluminoxane composition without using a solid support such as that set forth above. Generally, when attempting to prepare a solid polymethylaluminoxane composition, the method of reacting some additive with a liquid polymethylaluminoxane composition is adopted (see Patent References 12 to 16 and the like). However, in such methods, the recovery rate of the solid material based on aluminum is not high.    Patent Reference 1: JP-A-S58(1983)-19309    Patent Reference 2: JP-A-S60(1985)-35005    Patent Reference 3: JP-A-S62(1987)-234009    Patent Reference 4: JP-A-S63(1988)-234009    Patent Reference 5: JP-A-S64(1989)-66214    Patent Reference 6: JP-A-H01(1989)-207355    Patent Reference 7: JP-A-S60(1985)-260602    Patent Reference 8: JP-A-S63(1988)-89506    Patent Reference 9: JP-A-S63(1988)-178108    Patent Reference 10: JP-A-H01(1989)-315407    Patent Reference 11: JP-A-H02(1990)-22308    Patent Reference 12: JP-A-2000-95810    Patent Reference 13: JP-A-H08(1996)-319309    Patent Reference 14: JP-A-H07(1995)-300486    Patent Reference 15: JP-A-H07(1995)-70144    Patent Reference 16: JP-A-H07(1995)-42301    Patent Reference 17: JP-A-2000-505785(WO97/23288)The disclosures of Patent References 1 to 17 are expressly incorporated herein by reference in their entirety.